1. Field of the Invention
The present invention relates to a sheet storage apparatus that stores a sheet carried out of an image formation apparatus or the like on a stack tray, and more particularly, to improvements in the sheet alignment mechanism in collecting sheets in the shape of a bunch in a predetermined post-processing position.
2. Description of the Related Art
Generally, in this type of apparatus, sheets fed from an image formation apparatus or the like are carried in a sheet discharge path, and are stored on a stack tray disposed on the downstream side of a path sheet discharge outlet. Then, such an apparatus is widely known as an apparatus in which a processing tray (sub-tray) to temporarily mount and support sheets is provided between the sheet discharge outlet and the stack tray, sheets are collated and subjected to post-processing on the tray, and the processed bunch of sheets is carried out to the stack tray.
For example, in Patent Document 1 (Japanese Patent Gazette No. 4500713 (FIG. 1)) is proposed a post-processing apparatus provided with a sheet carry-in path coupled to a sheet discharge outlet of an image formation apparatus, a processing tray disposed on the downstream side of the path sheet discharge outlet, and a stack tray on the downstream side of the processing tray. Then, sheets fed from the image formation apparatus are switchback-transported from the sheet discharge outlet to the processing tray, and collated and collected. The bunch of sheets is subjected to staple binding or jog-offset, and is carried out to the stack tray on the tray downstream side.
Accordingly, in such an apparatus configuration, the sheet carry-in path, processing tray and stack tray are laid in the apparatus housing in this order, and the sheet is transported from the sheet discharge path on the upstream side to the stack tray on the downstream side in this order.
Further, in Patent Document 2 (Japanese Patent Gazette No. 4901082 (FIG. 1)), a stack tray is disposed with a height difference formed on the downstream side of a sheet carry-in path, and a sheet dropping from a sheet discharge outlet onto a tray load surface is temporarily mounted and held on a support member (sub-tray) disposed in the middle portion in the height difference. Then, a post-processing apparatus is disclosed in which the support member is configured to be able to shift between an actuation position above the tray load surface and a waiting position retracted to the outside of the tray.
It is possible to make the apparatus small and compact by adopting such a configuration for temporarily collecting sheets dropping from the sheet discharge outlet on the support member proceeding above the tray to perform post-processing, and then retracting the support member to the outside of the tray to store.